flea beetle

(Disonycha uniguttata)

               
Conservation Status

IUCN Red List

not listed

flea beetle (Disonycha uniguttata)

 

NatureServe

NNR - Unranked

Minnesota

not listed

Occurrence

 

Flight/Season

 

Habitat/Hosts

Knotweed (Polygonum)

Size

Total Length: ¼ to 5 16

          Photo by Alfredo Colon

Identification

Disonycha uniguttata is a small beetle, a moderate-sized leaf beetle, and a large flea beetle. It is found east of the Rocky Mountains.

Adults are somewhat shiny, slender, oblong, ¼ to 5 16 (6 to 8 mm) long, and 1 16 to (2.2 to 3.8 mm) wide.

The exoskeletal plate covering the thorax (pronotum) is about twice as wide as long and nearly as wide as the hardened forewings (elytra). The rear corners are truncated at an oblique angle. The lateral margin is bowed outward, narrow, and sharp. There is a slight depression in the middle of the pronotum (dorsally) near the base. The pronotum is red with a whitish margin, There is usually a large black spot in the middle and one small dark brown spot on each side. Sometimes the spots merge together.

The elytra are oblong with parallel sides, rounded in the shoulder (humeral) region, and broadly rounded at the tip. They have a narrow, flat, pale margin that does not extend all of the way to the tip. The surface is smooth, shiny, and hairless. It is distinctly and densely covered with pits that are not in rows. On the female there is no trace or only a faint trace of longitudinal ridges. Each elytrum is dingy white (pale) with inner (sutural), middle, and lateral black stripes. The sutural stripe extends to the tip of the elytrum, the lateral one does not. The black stripes are considerably broader than the pale ones. The plate between the wing bases (scutellum) is triangular and black.

The legs are relatively short and slender. The third segment (femur) of each leg is usually pale or red, sometimes dark. The outer edge of the fourth leg segment (tibia) is shallowly grooved, even on the hind legs, and has a short spur at the tip (apex). he last part of each leg (tarsus), corresponding to the foot, has five segments. The fourth segment is very short and is concealed within the broadened tip of the third segment, making the tarsus appear to have only four segments. The first segment is about twice as long as the second, and on the male it is much enlarged. The claw at the tip of the tarsus has a short tooth at the base. The joint on the hind claw is not inflated.

The head behind the eyes is covered by the pronotum. It may be entirely black but is usually pale or red at the base of the antennae. The space between the eyes is more than half the width of the head. The antennae are black and relatively long but less than half as long as the body. The basal segments are pale. The third segment is shorter than the fourth or fifth.

 
Similar
Species

 


Larval Food

Knotweed (Polygonum)

 
Adult Food

Knotweed (Polygonum)

 
Life Cycle

Adults overwinter. In the spring, the female lays eggs on or near a host plant.

 
Behavior

Larvae feed on the lower surface of the leaves of the host plant. Adults chew tiny “shotholes” in the leaf. They jump when disturbed.


Distribution Distribution Map  

Sources: 24, 29, 30.


Comments

Taxonomy
Flea beetles were formerly treated as the subfamily Alticnae. Disonycha uniguttata was formerly treated as a subspecies or synonym of Disonycha pensylvanica.


Taxonomy

Order:

Coleoptera (beetles)

 

Suborder:

Polyphaga (water, rove, scarab, longhorn, leaf and snout beetles)

 

Infraorder:

Cucujiformia

 

Superfamily:

Chrysomeloidea (long-horned and leaf beetles)

 

Family:

Chrysomelidae (leaf beetles)

 

Subfamily:

Galerucinae (skeletonizing leaf beetles)

 

Tribe:

Alticini (flea beetles)

 

Subtribe:

Disonychina

 

Genus:

Disonycha

 

Group:

pensylvanica

 
Synonyms

 

 
Common
Names

 


 

 

 

 

 

Glossary

Elytra

The hardened forewings on an insect used to protect the fragile hindwings, which are used for flying, in beetles and true bugs. Singular: elytrum.

 

Femur

On insects and arachnids, the third, largest, most robust segment of the leg, coming immediately before the tibia. On humans, the thigh bone.

 

Pronotum

The saddle-shaped, exoskeletal plate on the upper side of the first segment of the thorax of an insect.

 

Scutellum

The exoskeletal plate covering the rearward (posterior) part of the middle segment of the thorax in some insects. In Coleoptera, Hemiptera, and Homoptera, the dorsal, often triangular plate behind the pronotum and between the bases of the front wings. In Diptera, the exoskeletal plate between the abdomen and the thorax.

 

Tarsus

The last two to five subdivisions of an insect’s leg, attached to the tibia; the foot. Plural: tarsi.

 

Tibia

The fourth segment of an insect leg, after the femur and before the tarsus (foot).

 

 

 

 

 

       

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Alfredo Colon


  flea beetle (Disonycha uniguttata)    

       
       
       

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Alfredo Colon
6/12/2018

Location: Woodbury, Minnesota

flea beetle (Disonycha uniguttata)


     
     
 

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